Interbody Implant With Independent Control Of Expansion At Multiple Locations

ABSTRACT

Expandable spinal interbody implants include a body and at least one extendable support element connected thereto. Such an implant may include a second extendable support element and a tool selectively positionable with respect to the implant so as to independently or simultaneously expand both extendable support elements. In another example, such an implant may include, at each of a first and second location, a respective movable member and a respective locking element. The at least one extendable support element may be actuatable to expand so as to induce movement of at least one of the movable members away from the body. The locking elements at each of the first and second locations may be selectively lockable such that, when locked, the locking element restrains movement of the associated movable member at that location away from the body without restraining movement of the other movable member away from the body.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 15/702,171 filed Sep. 12, 2017, which claims the benefit of thefiling date of U.S. Provisional Patent Application No. 62/393,380 filedSep. 12, 2016, the disclosures of which are hereby incorporated hereinby reference.

BACKGROUND OF THE INVENTION

Intervertebral implants are commonly used in spinal surgery, such as ininterbody fusion procedures, in which an implant (e.g., a spacer orcage) is placed in the disc space between two vertebrae to be fusedtogether. At least a portion of the disc is typically removed before theimplant is positioned in the intervertebral space, and the implant maybe supplemented with bone graft material to promote fusion of thevertebrae. Interbody fusion procedures may also be performed inconjunction with other types of fixation, such as pedicle screwfixation, to provide additional stability, particularly while thevertebrae fuse together.

Different interbody fusion procedures can be distinguished by theirlocation along the spine (e.g., in the cervical, thoracic, or lumbarregions); by the type of implant used; and by the surgical approach tothe intervertebral space, in which different surgical approaches oftenimply different structural characteristics of the implant or implantsused. Different surgical approaches to the spine include anterior,posterior, and lateral. Examples of interbody fusion techniquesperformed along a posterior approach include posterior lumbar interbodyfusion (PLIF) and transforaminal lumbar interbody fusion (TLIF). PLIFtechniques typically include positioning two intervertebral implantsinto the intervertebral space along a posterior to anterior direction,with one implant being positioned towards the left side of the spine andone implant being positioned towards the right side of the spine. Theimplants used in such PLIF techniques typically have a straight shape,in that they extend along a central axis. TLIF techniques, by contrast,typically include positioning one intervertebral implant into theintervertebral space (often towards the anterior portion of theintervertebral space) from the posterior of the patient, but the spineis approached on one side from a more lateral position than in PLIFtechniques. The implants used in such TLIF techniques are often curved,such that they have an overall kidney bean-like shape. Interbody fusiontechniques performed along a lateral approach, on the other hand, ofteninvolve implants that are generally symmetric along their linearlongitudinal axis (e.g., having a substantially rectangular or ovalshape), but the implants are typically larger than those used in PLIF orTLIF techniques. That is, intervertebral implants used in lateralapproaches often cover a substantial portion of the disc space.

Included among the different types of intervertebral implants areexpandable implants. Such implants often have an initially contractedconfiguration, such that they have a low profile in thesuperior-inferior direction, in order to ease insertion into theintervertebral space. Such expandable implants can then be expanded inthe superior-inferior direction after implantation, so as to securelyengage and stabilize the vertebrae on both sides of the intervertebralspace. Examples of expandable intervertebral implants are disclosed inU.S. Pat. No. 8,992,620 (“the '620 Patent”) and in U.S. patentapplication Ser. No. 15/481,854 filed on Apr. 7, 2017, entitledExpandable Interbody Implant (hereinafter “the '854 Application”), thedisclosures of which are hereby incorporated by reference herein as iffully set forth herein.

Although considerable effort has been devoted in the art to optimizationof such intervertebral systems and methods, still further improvementwould be desirable.

BRIEF SUMMARY OF THE INVENTION

The present invention relates to expandable spinal interbody implants,as well as to systems comprising the same and methods of operating thesame.

In accordance with aspects of the invention, a spinal implant forplacement between first and second vertebral bodies preferably includesa body and at least first and second extendable support elementsconnected to the body at respective first and second locations. The bodymay have a first surface for engaging the first vertebral body. Thefirst and second extendable support elements are each desirablyconfigured to expand such that a respective first and second end of theextendable support element moves away from the body. A spinal implantsystem comprising such a spinal implant preferably further includes atool selectively positionable with respect to the implant so as toindependently or simultaneously expand the first and second extendablesupport elements.

According to some further aspects of the above spinal implant system,the spinal implant may be configured to allow the tool to move withinthe spinal implant to expand the first and second extendable supportelements. In some yet further aspects of such spinal implant system, thespinal implant may be configured to allow the tool to movelongitudinally within the spinal implant to expand the first and secondextendable support elements. According to some even further aspects,such spinal implant may include a channel extending between the firstand second extendable support elements, such that the longitudinalmovement of the tool is within the channel.

According to some other aspects of the above spinal implant system, eachof the first and second extendable support elements may include a pistonslidably received within a cylinder. In some yet further aspects of suchspinal implant system, the first and second extendable support elementsmay be configured to be extended by a fluid. According to some evenfurther aspects, the spinal implant may include a channel extendingbetween the first and second extendable support elements. In some suchaspects, the tool may supply the fluid to the first and secondextendable support elements, and the channel of the spinal implant maybe configured to allow the tool to move therealong to selectively supplythe fluid to the first and second extendable support elements. In someother of such aspects, the tool may include an internal fluidpassageway. In some even further aspects, the channel of the spinalimplant may be adapted to receive the tool therein, and, when the toolis received within the channel, an exterior fluid passageway may bedefined between an inner surface of the channel and an exterior surfaceof the tool. That exterior fluid passageway may communicate with theinternal fluid passageway via at least one exit port of the tool. Insome further aspects of such spinal implant system, the tool may belongitudinally movable along the channel, such that the exterior fluidpassageway can be moved to selectively communicate with either or bothof the first and second expandable support elements. In some otherfurther aspects of the spinal implant system, the exterior fluidpassageway may be defined between a first seal member and a second sealmember spaced apart along a length of the tool, which seal members maybe configured to sealingly engage the inner surface of the channel. Insome yet other further aspects of the spinal implant system, theexterior fluid passageway may be at least partially defined by arecessed portion of the exterior surface of the tool.

According to some other aspects of the above spinal implant system, thefirst end of the first extendable support element and the second end ofthe second extendable support element may be connected by a plate havinga second surface for engaging the second vertebral body. In some yetfurther aspects of such spinal implant system, the first end of thefirst extendable support element may be connected to the plate by afirst pivotable connection and the second end of the second extendablesupport element may be connected to the plate by a second pivotableconnection.

In accordance with other aspects of the invention, a spinal implant forplacement between first and second vertebral bodies preferably includesa body, at least one extendable support element connected to the body,first and second movable members having respective first and second endsmovable away from the body, and first and second locking elements. Thefirst movable member and the first locking element are preferably at afirst location, and the second movable member and the second lockingelement are preferably at a second location. The first and secondlocking elements are desirably selectively lockable such that, when thefirst locking element is locked, the first locking element restrainsmovement of the first movable member away from the body withoutrestraining movement of the second movable member away from the body,and, when the second locking element is locked, the second lockingelement restrains movement of the second movable member away from thebody without restraining movement of the first movable member away fromthe body.

According to some further aspects of the above spinal implant, the firstlocking element, when locked, may restrain movement of the first movablemember away from the body by defining a maximum amount of permittedmovement of the first movable member away from the body, and the secondlocking element, when locked, may restrain movement of the secondmovable member away from the body by defining a maximum amount ofpermitted movement of the second movable member away from the body. Insome yet further aspects of such spinal implant, the first lockingelement may be configured to selectively vary the maximum amount ofpermitted movement of the first movable member away from the body whenthe first locking element is locked, and the second locking element maybe configured to selectively vary the maximum amount of permittedmovement of the second movable member away from the body when the secondlocking element is locked.

According to some other aspects of the above spinal implant, the firstand second locking elements may each be rotatable so as to move betweena locked configuration and an unlocked configuration. In some yetfurther aspects of such spinal implant, the first and second lockingelements may each have a cylindrical shape defining an open interiorspace. According to some even further aspects, the extendable supportelement may include a first extendable support element and a secondextendable support element, with the first extendable support elementbeing received within the open interior space of the first lockingelement, and the second extendable support element being received withinthe open interior space of the second locking element. In some evenfurther aspects, an inner surface of the first locking element mayinclude a first inner projecting feature, and an outer surface of thefirst extendable support element may include a first outer projectingfeature. The first inner projecting feature and the first outerprojecting feature may be arranged to selectively engage and disengageone another based on a rotational position of the first locking element.An inner surface of the second locking element may similarly include asecond inner projecting feature, and an outer surface of the secondextendable support element may include a second outer projectingfeature. The second inner projecting feature and the second outerprojecting feature may likewise be arranged to selectively engage anddisengage one another based on a rotational position of the secondlocking element. In some such aspects, the first inner projectingfeature, the first outer projecting feature, the second inner projectingfeature, and the second outer projecting feature may each include aplurality of projecting ribs. In some other of such aspects, the firstinner projecting feature may include a series of first projecting ribs,each of which may extend to a different radial position along the innersurface of the first locking element, and the second inner projectingfeature may include a series of second projecting ribs, each of whichmay extend to a different radial position along the inner surface of thesecond locking element. According to some aspects, the first lockingelement may include a plurality of teeth along an outer surface of thefirst locking element, which teeth may be adapted for engagement by afirst control tool to rotate the first locking element so as to move thefirst locking element between a locked configuration and an unlockedconfiguration.

According to some other aspects of the above spinal implant, theextendable support element may include a first extendable supportelement and a second extendable support element, with the first movablemember being a portion of the first extendable support element, and thesecond movable member being a portion of the second extendable supportelement.

According to some other aspects of the above spinal implant, the firstand second movable members may be connected by a plate having a secondsurface for engaging the second vertebral body. In some yet furtheraspects of such spinal implant, the first and second movable members areconnected to the plate by a respective first and second pivotableconnection.

In accordance with yet other aspects of the invention, a spinal implantsystem may comprise a spinal implant, as described above, and first andsecond control rods. The first and second control rods are desirablyadapted to selectively lock the respective first and second lockingelements of the implant.

According to some further aspects of the above spinal implant system,the first and second control rods may be adapted to selectively lock therespective first and second locking element by linear movement of therespective first and second control rod within the spinal implant. Insome yet further aspects of such spinal implant system, the first andsecond control rods may each include a plurality of teeth arranged toengage the respective first and second locking elements so as to controlthe selective locking of the respective first and second lockingelements.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a spinal implant system in accordancewith one embodiment of the present invention.

FIGS. 2A-C are cross-sectional plan views about line 2-2 of theembodiment of FIG. 1 in different configurations.

FIG. 3A is a side elevation view of an embodiment of a spinal implantsystem having a top end plate.

FIG. 3B is a perspective view of the spinal implant system of FIG. 3A.

FIG. 4 is an exploded, perspective view of a spinal implant system inaccordance with another embodiment of the present invention.

FIG. 5 is a perspective view of the spinal implant system of FIG. 4.

FIG. 6 is a perspective, side cross-sectional view about thelongitudinal axis of the spinal implant system of FIG. 4.

FIG. 7 is a cross-sectional side elevation view about the longitudinalaxis of the spinal implant system of FIG. 4.

FIG. 8 is a cross-sectional rear elevation view about line 8-8 in FIG.7.

FIG. 9 is a perspective, bottom cross-sectional view of the spinalimplant system of FIG. 7 about line 9-9.

FIG. 10 is a cross-sectional side elevation view about the longitudinalaxis of a variation on the embodiment of FIG. 4.

FIG. 11 is a perspective, top cross-sectional view of the spinal implantsystem of FIG. 7 about line 11-11.

FIGS. 12A-B are plan views of locking components of the embodiment ofFIG. 4 in different configurations.

FIG. 13A is a cross-sectional plan view about line 13-13 of thealternative locking component illustrated in FIG. 10 in a lockedconfiguration.

FIG. 13B is a side, cross-sectional view about the implant'slongitudinal axis of the locking component of FIG. 13A in a lockedconfiguration.

FIG. 13C is a cross-sectional plan view about line 13-13 of thealternative locking component illustrated in FIG. 10 in an unlockedconfiguration.

FIG. 13D is a side, cross-sectional view about the implant'slongitudinal axis of the locking component of FIG. 13A in an unlockedconfiguration.

FIG. 14 is a perspective view of the spinal implant system of FIG. 4including a delivery tool.

FIG. 15 is a perspective view of a locking element in accordance withanother embodiment of the invention.

FIGS. 16A-B are exploded, perspective views (taken from differentangles) of a spinal implant system in accordance with an embodiment ofthe invention including the locking element of FIG. 15.

FIG. 17 is a cross-sectional plan view about line 17-17 of the spinalimplant system of FIG. 16B.

FIG. 18 is a cross-sectional side elevation view about the longitudinalaxis of the spinal implant system of FIG. 17.

FIG. 19 is a bottom cross-sectional view about line 19-19 of the spinalimplant system of FIG. 16B.

FIG. 20 is a cross-sectional side elevation view about the longitudinalaxis of a spinal implant system in accordance with another embodiment ofthe present invention.

DETAILED DESCRIPTION

FIGS. 1-3 illustrate components of an intervertebral implant system 1 inaccordance with an embodiment of the present invention. The system 1includes an implant 10 having a body or housing 11 and multipleextendable support elements that are expandable such that their top ends5 are movable away from the housing 11. The extendable support elementsmay be in the form of any of the extendable support elements disclosedin the '620 Patent or the '854 Application. For example, as shown, theextendable support elements are in the form of pistons 22 a and 22 bslidably received within a corresponding pair of cylinders 16 a and 16 bdefined within the housing 11. The sliding of the pistons 22 a, 22 balong the cylinders 16 a, 16 b results in the translation of the topends 5 of the pistons 22 a, 22 b so as to expand the implant 10. Thepistons 22 a, 22 b and cylinders 16 a, 16 b may operate as part of ahydraulic system, in which the sliding of the pistons 22 a, 22 b awayfrom the bottoms of the cylinders 16 a, 16 b is driven by pressurizedfluid within the cylinders, as discussed in the '620 Patent and the '854Application. Although not shown in FIGS. 1-3, the implant 10 may alsoinclude a locking system to lock the positions of the pistons 22 a, 22b, at least by preventing them from translating back towards the housing11 once expanded. The locking system may include any of the structuresof the locking systems disclosed in the '620 Patent and the '854Application, and the locking system may also be unlockable to allow thepistons to collapse (e.g., to reposition the implant 10 or to remove itfrom the body).

As discussed below, each extendable support element (e.g., piston 22)can be independently actuated so as to independently expand with respectto the housing 11. The bottom 12 of the housing 11 has a bottom endsurface 8, which is a bone engaging surface for engaging a vertebra onone side (e.g., the inferior side) of the intervertebral space withinwhich the implant 10 is positioned. The top ends 5 of the pistons 22 a,22 b may represent bone engaging surfaces of the implant 10 for engaginga vertebra on the opposite side of the intervertebral space from thebottom end surface 8 (e.g., the superior side). Alternatively, eachpiston top end 5 may be connected to a respective plate element (notshown) that has a top end surface representing a bone engaging surfacefor engaging the vertebra on the opposite side of the intervertebralspace from the bottom end surface 8, similar to the plate elements inthe embodiment of FIGS. 4-8. In yet a further alternative, both pistontop ends 5 may be connected to a common top end plate 13 having a topend surface 9 representing a bone engaging surface for engaging thevertebra on the opposite side of the intervertebral space from thebottom end surface 8, as shown in FIGS. 3A-B. In such an embodiment, thetop end plate 13 may be connected to each piston 22 a, 22 b by apivotable connection, such as a rotatable pin connection, so that thetop end plate 13 can be angled with respect to each piston 22 a, 22 b toaccommodate different amounts of translation of each piston 22 a, 22 b.

The intervertebral implant system 1 in accordance with the presentinvention also includes a tool for actuating the expansion of theextendable support elements. The tool may include a fluid deliverycannula 63 for delivering a pressurized fluid to the cylinders 16 a, 16b in order to drive the translation of the pistons 22 a, 22 b. The fluiddelivery cannula 63 is in the form of a shaft having an internal fluidpassageway 65 extending along its length. The fluid delivery cannula 63is desirably configured to independently control the expansion of eachextendable support element. The fluid delivery cannula 63 may also beconfigured to control the expansion of both extendable support elementsat the same time. For example, the fluid delivery cannula 63 isselectively positionable within a pressure channel 41 extending betweenboth of the cylinders 16 a, 16 b, which channel 41 communicates witheach of the cylinders 16 a, 16 b via a respective opening 71. The fluiddelivery cannula 63 can thus selectively communicate with either or bothof the cylinders 16 a, 16 b based on its longitudinal position withinthe channel 41. In that regard, when the fluid delivery cannula 63 isreceived within the channel 41, an exterior fluid passageway 67 isdefined between an inner surface of the channel 41 and an exteriorsurface of the fluid delivery cannula 63. The longitudinal extent of theexterior fluid passageway 67 may be defined by a distal seal member 73,which may be in the form of an o-ring positioned around the exteriorsurface of the fluid delivery cannula 63 towards its distal end, and aproximal seal member 75, which may also be in the form of an o-ringpositioned around the exterior surface of the fluid delivery cannula 63and spaced proximally from the distal seal member 73. The volume of theexterior fluid passageway 67 may also be defined by a recessed groove 69within the exterior surface of the fluid delivery cannula 63. As shownin FIGS. 2A-C, that recessed groove 69 may be an annular groove thatextends entirely around the circumference of the fluid delivery cannula63 between the distal and proximal seal members 73, 75. The fluid fromthe internal fluid passageway 65 may thus be communicated to theexternal fluid passageway 67 via at least one exit port 77 in the fluiddelivery cannula 63.

In order to selectively actuate the extendable support elements, thefluid delivery cannula 63 can be appropriately positioned along thechannel 41 as shown in FIGS. 2A-C. That is, as shown in FIG. 2A, whenthe fluid delivery cannula 63 is positioned at the distal-most end ofthe channel 41, the external fluid passageway 67 between the distal andproximal seal members 73, 75 communicates with the opening 71 of thedistal cylinder 16 a, but not with the opening 71 of the proximalcylinder 16 b. Thus, the supply of pressurized fluid through the fluiddelivery cannula 63 in the position illustrated in FIG. 2A will causeexpansion of the distal piston 22 a only. By retracting the fluiddelivery cannula 63 to the position illustrated in FIG. 2B, the externalfluid passageway 67 communicates with the openings 71 of both the distaland proximal cylinders 16 a, 16 b. Thus, in the position illustrated inFIG. 2B, the supply of pressurized fluid through the fluid deliverycannula 63 will cause expansion of both pistons 22 a, 22 b. Finally,further retraction of the fluid delivery cannula 63 to the positionillustrated in FIG. 2C will cause the external fluid passageway 67 tocommunicate with the opening 71 of the proximal cylinder 16 b but notthe distal cylinder 16 a. Thus, supply of pressurized fluid through thefluid delivery cannula 63 in the position illustrated in FIG. 2C willcause expansion of the proximal piston 22 b only.

By manipulating the fluid delivery cannula 63 as discussed above, theexpansion of the different extendable support elements can beindividually controlled. That may be useful, for example, in order toadjust the height of each extendable support element to best fit theanatomy of the patient. Individual adjustment may also be useful forproviding a specific angular correction to the patient's spine. Forexample, by providing greater expansion at the anterior portion of thespine than the posterior portion of the spine, the implant 10 maydecompress nerve roots while also providing lordosis correction.

The above-described embodiment illustrated in FIGS. 1-3 is desirablystructured to be used in a PLIF technique. That is, the generally linearshape of the implant 10 between the distal and proximal ends of theimplant may be particularly suitable for inserting two such implants 10into an intervertebral space (one on either side of the spine) along aposterior to anterior direction, such that the distal end of the implantis positioned more anteriorly with respect to the spine than the moreposteriorly positioned proximal end of the implant. However, the sameoperative components discussed above can also be included in implantsstructured to be used in a TLIF technique or along a lateral approach.For example, an implant structured to be used in a lateral approach mayhave a similar configuration to that discussed above, but may be sizedto cover a substantial portion of the disc space. As for an implantstructured to be used in a TLIF technique, the same operative componentsdiscussed above can be incorporated into an implant having an overallkidney bean-like shape. In such an embodiment, the channel for receivingthe fluid delivery cannula may be linear between the cylinders, as shownin the above-discussed figures, or it may follow an arcuate path. If thechannel is arcuate, the fluid delivery cannula may have a correspondingarcuate shape or may be flexible to conform to the path of the channel.

Although the embodiment of FIGS. 1-3 allows for individual control ofthe amount of expansion at different locations along the implant 10 byallowing for individual actuation of the extendable support elementspositioned at different locations within the implant 10, similarindividual control of the amount of expansion at different locationsalong the implant 10 may be provided in other ways. For example, in theembodiment of FIGS. 4-12, discussed below, the same expansion pressuremay be simultaneously applied to the different locations along theimplant 110, while those different locations can be individually lockedto restrain expansion at the selected location(s) during the applicationof such expansion pressure.

FIGS. 4-5 illustrate components of an intervertebral implant system 101in accordance with another embodiment of the present invention. Thesystem 101 includes an implant 110 having a body or housing 111 andmultiple extendable support elements that are each expandable such thattheir top ends 105 are movable away from the housing 111. The extendablesupport elements may be in the form of any of the extendable supportelements disclosed in the '620 Patent or the '854 Application. Theextendable support elements may also be in the form of pistons 122 a and122 b slidably received around associated cylindrical posts 116 a, 116 baffixed to the housing 111, as shown in FIGS. 4 and 6-8. For example, inthe illustrated embodiment, the pistons 122 a and 122 b may be hollow,cylindrical structures received around associated posts 116 a, 116 b,which posts 116 a, 116 b may also be hollow, cylindrical structureshaving respective pressure channels 141 a at their bottom ends forsupplying pressurized fluid. A seal member 123, which may be in the formof an o-ring, may be positioned so as to seal the sliding interfacesbetween the pistons 122 a, 122 b and the respective posts 116 a, 116 b,in order to prevent the pressurized fluid from escaping through thoseinterfaces. The pistons 122 a, 122 b and posts 116 a, 116 b may thusoperate as part of a hydraulic system like that discussed in the '620Patent and the '854 Application. In particular, when pressurized fluidis supplied to the area defined between the posts 116 a, 116 b andrespective pistons 122 a, 122 b, the pressurized fluid will drive thepistons 122 a, 122 b to slide outward from the housing 111.

As shown in FIGS. 4 and 6-9, the posts 116 a, 116 b may be portions ofrespective plug elements 114 a, 114 b affixed to the housing 111 bybeing secured within respective cylindrical bores 115 a, 115 b formedthrough the housing 111. The plug elements 114 a, 114 b may have wide,circular base plates 117 a, 117 b, which may be secured within thebottoms of the respective bores 115 a, 115 b. Separate alignment rings119 a, 119 b may be secured (e.g., welded) within the tops of therespective bores 115 a, 115 b after the pistons 122 a, 122 b have beenpositioned within the bores 115 a, 115 b, in order to secure and alignthe pistons 122 a, 122 b within the implant. Such alignment rings 119 a,119 b may have outer dimensions matching the inner dimensions of thebores 115 a, 115 b, and inner dimensions matching the outer profiles ofthe respective pistons 122 a, 122 b. For example, the inner profiles ofthe alignment rings 119 a, 119 b may include inwardly projectingportions or flat surfaces 124 that match recesses 146 along the outersurfaces of the pistons 122 a, 122 b, in order to constrain therotational orientations of the pistons 122 a, 122 b. The alignment rings119 a, 119 b may also act as a stop to prevent further expansion of thepistons 122 a, 122 b beyond a predetermined height. For example, thepistons 122 a, 122 b may each include at least one projecting featurethat will engage the underside of the respective alignment rings 119 a,119 b to prevent further expansion of the pistons. The posts 116 a, 116b of the plug elements 114 a, 114 b may have pressure channels 141 aformed therein, which communicate with a network of pressure channels141 b and 141 c formed in the housing 111, as shown in FIGS. 8-9. Thatis, the housing 111 includes a longitudinal pressure channel 141 bcommunicating with a pressure input port 138, into which the pressurizedfluid is supplied. The network of pressure channels formed in thehousing 111 may also include transverse pressure channels 141 cextending from the longitudinal pressure channel 141 b and communicatingwith the pressure channels 141 a formed in the base plates 117 a, 117 bof the plug elements 114 a, 114 b. The longitudinal and transversepressure channels 141 b, 141 c may be formed by drilling bores intosidewalls of the housing 111, after which plugs (not shown) may beinserted into the resulting openings formed in the sidewalls, such thatthe only remaining openings into the channel system are the pressureinput port 138 and the exits into the pistons 122 a, 122 b.

The bottom 112 of the housing 111 has a bottom end surface 108, which isa bone engaging surface for engaging a vertebra on one side (e.g., theinferior side) of the intervertebral space within which the implant 110is positioned. The top ends 105 of the pistons 122 a, 122 b mayrepresent bone engaging surfaces of the implant 110 for engaging avertebra on the opposite side of the intervertebral space from thebottom end surface 108 (e.g., the superior side). Alternatively, the topend 105 of each piston 122 a, 122 b may be connected to a respectiveplate element 113 a, 113 b that has a top end surface 109 representing abone engaging surface for engaging the vertebra on the opposite side ofthe intervertebral space from the bottom end surface 108, as shown inFIGS. 4-8. In yet a further alternative, both piston top ends 105 may beconnected to a common top end plate 113 having a top end surface 109representing a bone engaging surface for engaging the vertebra on theopposite side of the intervertebral space from the bottom end surface108, as shown in FIG. 10. In such an embodiment, the top end plate 113may be connected to each piston 122 a, 122 b by a pivotable connection107 a, 107 b, such as a rotatable pin connection, so that the top endplate 113 can be angled with respect to each piston 122 a, 122 b toaccommodate different amounts of translation of each piston 22 a, 22 b.

The implant 110 also includes a locking system having multiple lockingelements 120 a, 120 b secured to the housing 111 and configured to lockthe translational positions of the pistons 122 a, 122 b. The lockingelements 120 a, 120 b may have a cylindrical shape configured to bepositioned around the respective pistons 122 a, 122 b. The lockingelements 120 a, 120 b may include at least one feature projectinginwardly from an inner surface thereof, and the pistons 122 a, 122 b mayinclude at least one corresponding feature projecting outwardly from anouter surface thereof. Those features are configured to engage anddisengage one another by rotation of the locking elements 120 a, 120 bwith respect to the pistons 122 a, 122 b. For example, as shown in FIG.4, the pistons 122 a, 122 b may each include a series of spaced apartribs 118 projecting from their outer surfaces, and the inner surfaces ofthe locking elements 120 a, 120 b may each include a series of spacedapart ribs 121. In particular rotational orientations of each lockingelement 120 a, 120 b (referred to as a “locked configuration”), the ribs121 of the locking element 120 a, 120 b mesh with the ribs 118 of theassociated piston 122 a, 122 b, thus preventing expansion the piston 122a, 122 b. The ribs 121 of the locking elements 120 a, 120 b may bestructured and arranged to align and fit within the recesses 146 alongthe outer surfaces of the pistons 122 a, 122 b at particular rotationalpositions of each locking element 120 a, 120 b (referred to as an“unlocked configuration”). In the unlocked configuration, there isclearance between the ribs 118 of a piston 122 a, 122 b and the ribs 121of the associated locking element 120 a, 120 b, thus leaving the pistons122 a, 122 b free to translate outwardly under the influence of thepressurized fluid, or free to translate back inwardly so as to collapsethe implant if the fluid is depressurized or withdrawn.

A rack-and-pinion arrangement may be used to control the rotationalpositions of the locking elements 120 a, 120 b, and thus the locked andunlocked status of the associated pistons 122 a, 122 b, as shown in FIG.11. For example, each locking element 120 a, 120 b may include aplurality of teeth 164 on the outer surface thereof, in order to engageteeth 170 of a corresponding control rod 168 a, 168 b, such that therotational position of each locking element 120 a, 120 b may becontrolled by the linear position of the control rod 168 a, 168 b withina channel 166 a, 166 b in the implant housing 111. As shown in FIG. 12A,in which the control rods 168 a, 168 b are advanced to a distal-mostposition, the locking elements 120 a, 120 b are in an unlockedconfiguration, such that the ribs 121 of the locking elements 120 a, 120b are aligned with the recesses 146 of the pistons 122 a, 122 b, andthus the pistons 122 a, 122 b are free to translate outwardly. Byretracting the control rods 168 a, 168 b proximally, as shown in FIG.12B, the locking elements 120 a, 120 b are moved to a lockedconfiguration, such that the ribs 121 of the locking elements 120 a, 120b are rotated into engagement with the ribs 118 of the pistons 122 a,122 b, thus preventing the pistons 122 a, 122 b from translatingoutwardly.

In the arrangement of FIGS. 12A-B, each piston 122 a, 122 b includestwo, diametrically opposed recesses 146, and the locking elements 120 a,120 b each include two corresponding sets of ribs 121. In an alternativearrangement, rather than a series of spaced apart ribs 118, only asingle rib 118 may be provided on each piston 122 a, 122 b. That singlerib 118 may be discontinuous in particular circumferential regions withwhich the ribs 121 of the locking elements 120 a, 120 b align in theunlocked configuration, so that there is clearance for the pistons 122a, 122 b to translate. As shown in FIGS. 13A-D, which are views of suchan alternative arrangement as incorporated into the embodiment of theimplant 110 of FIG. 10, the pistons 122 a, 122 b may include three suchdiscontinuous regions, although more or fewer discontinuous regions arealso within the scope of the present invention. As illustrated in thelocked configuration shown in FIGS. 13A-B, the ribs 121 of the lockingelement 120 are rotationally aligned with the solid portions of the rib118 of the piston 122, and thus the piston 122 is prevented fromtranslating outwardly. As for the unlocked configuration illustrated inFIGS. 13C-D, the ribs 121 of the locking element 120 have rotated intoalignment with the discontinuous regions of the rib 118 of the piston122, such that the piston 122 is free to translate outwardly. Thereverse arrangement (not shown) is also within the scope of the presentinvention. That is, instead of a series of spaced apart ribs 121 on thelocking elements 120 a, 120 b, only a single rib 121 havingdiscontinuous regions may be provided on the inner surface of eachlocking element 120 a, 120 b. Thus, in order to lock one of the pistons122 a, 12 b at its current level of displacement, the rib 121 of one ofthe locking elements 120 a, 120 b may be rotated into engagement withwhichever rib 118 of the associated piston 122 a, 122 b is at thatlevel.

By manipulating the control rods, and thus the locked and unlockedconfigurations of the pistons, as discussed above, the expansion of thedifferent pistons can be individually controlled while applying a singlefluid pressure to all the pistons. For example, by applying a pressureto the pressure channels sufficient to expand all of the pistons, anyone or more of the pistons can be selectively locked by appropriatemanipulation of the position of the associated control rod, such thatthe remaining unlocked pistons continue to translate outward from theimplant housing.

In order to control the translational position of the control rods 168a, 168 b, a delivery tool 100 for inserting and positioning the implant110 within the intervertebral space may include respective sliders 105a, 105 b linearly movable by a user along at least a portion of thedelivery tool 100, as shown in FIG. 14. The delivery tool 100 may besecurely attached to the proximal end of the implant 110 by a deliverytool anchor 137 (see FIGS. 4-7), which may include a threaded boreformed in the implant 110. In addition, the delivery tool 100 mayinclude a conduit for communicating with the pressure input port 138, inorder to supply the pressurized fluid to the implant 110. The deliverytool anchor 137 having a threaded bore for secure attachment to thedelivery tool 100 need not be a separate opening in the implant 110 fromthe pressure input port 139 for supplying pressurized fluid, and bothfunctions can be performed by a common opening, as shown in theembodiment of FIGS. 16-19. The locking elements 120 a, 120 b aredesirably configured such that fully retracting the associated controlrods 168 a, 168 b from the implant 110, such as when the delivery tool100 is disconnected and removed from the patient's body, will leave thelocking elements 120 a, 120 b in a locked configuration.

A further alternative embodiment in accordance with the presentinvention includes rotatable locking elements 220 similar to those ofthe embodiment of FIGS. 4-13D, except that the locking elements 220 areconfigured to selectively define a maximum amount of permitted movementof the associated piston 222, rather than locking the position of theassociated piston 222. For example, as shown in FIG. 15, the innersurface of the locking element 220 includes a series of spaced apartribs 221, where each successive rib 221 extends to a different,increasing circumferential position along the inner surface of thelocking element 220. Moreover, the associated piston 222 may include apin 218 projecting from its outer surface. Thus, each locking element220 can be rotated to a desired position so as to define a maximumamount of expansion of the associated piston 222, by aligning the rib221 corresponding to the desired height such that it is vertically abovethe pin 218. In that manner, expansion of the piston 222 by thepressurized fluid will cause the piston to translate until it engagesand stops at the aligned rib 221. The height of the piston 222 may thenbe locked at that position by fully retracting the associated controlrod 268, thus rotating the locking element 220 until the pin 218 isconstrained between two adjacent ribs 221. Each locking element 220 andpiston 222 combination need not have only one pin 218 and onecorresponding series of ribs 221, however. In alternative embodiments,multiple pins 218, each with a corresponding series of ribs 221, may beequally spaced apart about the circumference of the piston 218 andlocking element 220. For example, the embodiment illustrated in FIGS.16-17 has three pins 218 equally spaced about the circumference of eachpiston 222.

FIGS. 16-19, in which reference numerals like those in earlierembodiments refer to analogous elements (and therefore not all numberedelements will be separately discussed again), illustrate an embodimentof an implant 210 having distal and proximal locking elements 220 a, 220b like that shown in FIG. 15. Thus, in such an embodiment, the lockingelements 220 a, 220 b may be individually controlled by respectivecontrol rods 268 a, 268 b so that the associated pistons 222 a, 222 bcan be expanded to different desired heights, and the bone engagingcomponent(s) (e.g., top end plate 213) can thus be translated andangled, as with the previously-discussed embodiments. Many of the otherstructures of the embodiment of FIGS. 16-19 are substantially the sameas those of the embodiment of FIGS. 4-13D, except that, instead of theposts 116 a, 116 b along which the pistons 122 a, 122 b slide beingportions of respective plug elements 114 a, 114 b, the posts 216 a, 216b of the embodiment of FIGS. 16-19 may be portions of a single bottomplate element 214. As shown in FIG. 19, that plate element 214 mayinclude a network of longitudinal and transverse pressure channels 241b, 241 c similar to those of the embodiment of FIGS. 4-13D, such thatthe network of channels communicates the pressurized fluid from apressure input port 238 to the pistons 222 a, 222 b. The pressure inputport 238 may include a threaded section for secure attachment to adelivery tool for delivering the implant 210, such that the pressureinput port 238 also functions like the delivery tool anchor 137discussed above. A sealing member, such as o-ring 239, may also beprovided within the pressure input port 238, so as to seal the fluidconnection between the pressure input port 238 and the delivery tool.

Other differences between the embodiment of FIGS. 16-19 and theembodiment of FIGS. 4-13 include the fact that the embodiment of FIGS.16-19 does not have separate alignment rings like those illustrated inFIGS. 16A-B. Instead, similarly shaped alignment components may beintegrally formed with the housing 211 of the implant 210, or the bores215 a, 215 b through the housing 211 may be shaped to constrain therotational orientations of the pistons 222 a, 222 b. Also, as shown inFIG. 16A, the channel 266 a for the control rod 268 a that controls thedistal locking element 220 a opens outwardly through a side wall of thehousing 211 along a portion of the longitudinal extent of the housing211. Such extended opening into the channel 266 a through the side wall,which may beneficially allow for more clearance between the control rod268 a and the proximal locking element 220 b that it bypasses, may alsobe included in the embodiment of FIGS. 4-13, although not shown in thosefigures. The embodiment of FIGS. 16-19 also includes friction rings 225a, 225 b compressed between the tops of the locking elements 220 a, 220b and the underside of the top of the housing 221 in the assembledconfiguration. The friction rings 225 a, 225 b may be made out of rubberor a polymeric material that has a relatively high coefficient offriction, so that there is enough resistance to rotation of the lockingelements 220 a, 220 b that their rotational positions are maintainedwhen not intentionally rotated by the user using the control rods 268 a,268 b. Such friction rings, although not shown in FIGS. 4-13, can alsobe used in the embodiment of those figures.

The above-described embodiments illustrated in FIGS. 4-19 are desirablystructured to be used in a PLIF technique. That is, the generally linearshape of each of the implants 110, 210 between the distal and proximalends of the implant may be particularly suitable for inserting two suchimplants 110, 210 into an intervertebral space (one on either side ofthe spine) along a posterior to anterior direction, such that the distalend of the implant is positioned more anteriorly with respect to thespine than the more posteriorly positioned proximal end of the implant.However, the same operative components discussed above can also beincluded in implants structured to be used in a TLIF technique or alonga lateral approach. For example, an implant structured to be used in alateral approach may have a similar configuration to one of thosediscussed above, but may be sized to cover a substantial portion of thedisc space. As for an implant structured to be used in a TLIF technique,the same operative components discussed above can be incorporated intoan implant having an overall kidney bean-like shape. In such anembodiment, the channels for receiving the control rods may be linearbetween the locking elements, as shown in the above-discussed figures,or the channels may follow an arcuate path. If the channels are arcuate,the control rods may have a corresponding arcuate shape or may beflexible to conform to the paths of the channels.

Although the locking elements in the embodiments of FIGS. 4-19 arestructured to surround the associated pistons, alternative embodimentsin accordance with the present invention need not be arranged in thatmanner. For example, in another embodiment of the invention illustratedin FIG. 20, a single extendable support element, which may include atranslating piston 322 driven by a pressurized fluid, may be providedbetween a housing 311 of the implant 310 and a top end plate 313.Reference numerals in FIG. 20 that are like those in earlier embodimentsrefer to analogous elements, and therefore not all numbered elementswill be separately discussed again. The implant of FIG. 20 may includetwo or more locking elements 320 similar to those discussed above atdifferent locations across the implant 310, in order to individuallycontrol the amount of expansion of the top plate 313 at the location ofeach locking element 320. For example, the implant 310 may include adistal locking element 320 a and a proximal locking element 320 b, withthe extendable support element (e.g., piston 322) being centrallylocated therebetween. In operation, the extendable support element maybe actuated to drive the movement of the top end plate 313 away from thehousing of the implant, and each locking element 320 a, 320 b can beindividually manipulated to control the amount of expansion of the topend plate 313 at the distal and proximal ends. Rather than engagingextendable support elements positioned therein, the locking elements 320a, 320 b may each be configured to lock the expanded position of the topend plate 313 at the location of the locking element by lockinglyengaging a structure connected to the top end plate 313. For example,the top end plate 313 may include downwardly extending shafts 326 a, 326b coupled thereto, which shafts have outer surfaces with similarconfigurations to the pistons described above (i.e., each having aseries of spaced apart ribs projecting from the outer surface), wherethe shafts 326 a, 326 b are received within open interior regions of therespective locking elements 320 a, 320 b and are lockingly engageable bythe locking elements in similar ways to those described above (e.g., byrotational engagement with inwardly projecting ribs 321 of the lockingelements). The top end plate 313 may be indirectly coupled to thehousing 311 (e.g., via the extendable support element and/or lockingelements) by pivotable connections, so that the top end plate 313 canachieve angled orientations with respect to the housing 311 and so thatthe top end plate 313 can continue to translate at the location of alocking element 320 that is in an unlocked configuration, even when theother locking element is in a locked configuration. For example, asshown in FIG. 20, the shafts 326 a, 326 b may be coupled to the top endplate 313 by respective pivotable connections 307 a, 307 b, such asrotatable pin connections, and the piston 322 may contact the plate 313in such a way that the contact point can slide along the plate, so as tonot over-constrain the top end plate 313.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

1. A spinal implant system, comprising: a spinal implant for placementbetween first and second vertebral bodies, the spinal implant including:a body having a first surface for engaging a first vertebral body; afirst extendable support element connected to the body at a firstlocation, the first extendable support element being configured toexpand such that a first end of the first extendable support elementmoves away from the body; and a second extendable support elementconnected to the body at a second location, the second extendablesupport element being configured to expand such that a second end of thesecond extendable support element moves away from the body; and a toolselectively positionable with respect to the spinal implant so as toindependently or simultaneously expand the first and second extendablesupport elements.
 2. The spinal implant system of claim 1, wherein thespinal implant is configured to allow the tool to move within the spinalimplant to expand the first and second extendable support elements. 3.The spinal implant system of claim 2, wherein the spinal implant isconfigured to allow the tool to move longitudinally within the spinalimplant to expand the first and second extendable support elements. 4.The spinal implant system of claim 3, wherein the spinal implantincludes a channel extending between the first and second extendablesupport elements, such that the longitudinal movement of the tool iswithin the channel.
 5. The spinal implant system of claim 1, whereineach of the first and second extendable support elements includes apiston slidably received within a cylinder.
 6. The spinal implant systemof claim 5, wherein the first and second extendable support elements areconfigured to be extended by a fluid.
 7. The spinal implant system ofclaim 6, wherein the spinal implant includes a channel extending betweenthe first and second extendable support elements.
 8. The spinal implantsystem of claim 7, wherein the tool supplies the fluid to the first andsecond extendable support elements, and wherein the channel of thespinal implant is configured to allow the tool to move therealong toselectively supply the fluid to the first and second extendable supportelements.
 9. The spinal implant system of claim 7, wherein the toolincludes an internal fluid passageway.
 10. The spinal implant system ofclaim 9, wherein, the channel of the spinal implant is adapted toreceive the tool therein, and wherein, when the tool is received withinthe channel, an exterior fluid passageway is defined between an innersurface of the channel and an exterior surface of the tool, the exteriorfluid passageway communicating with the internal fluid passageway via atleast one exit port of the tool.
 11. The spinal implant system of claim10, wherein the tool is longitudinally movable along the channel, suchthat the exterior fluid passageway can be moved to selectivelycommunicate with either or both of the first and second extendablesupport elements.
 12. The spinal implant system of claim 10, wherein theexterior fluid passageway is defined between a first seal member and asecond seal member spaced apart along a length of the tool, the firstand second seal members being configured to sealingly engage the innersurface of the channel.
 13. The spinal implant system of claim 10,wherein the exterior fluid passageway is at least partially defined by arecessed portion of the exterior surface of the tool.
 14. The spinalimplant of claim 1, wherein the first end of the first extendablesupport element and the second end of the second extendable supportelement are connected by a plate having a second surface for engaging asecond vertebral body.
 15. The spinal implant of claim 14, wherein thefirst end of the first extendable support element is connected to theplate by a first pivotable connection and the second end of the secondextendable support element is connected to the plate by a secondpivotable connection.
 16. A system, comprising: an implant for placementbetween first and second vertebral bodies, comprising: a body having afirst surface for engaging a first vertebral body; a first extendablesupport element connected to the body and having a first end movableaway from the body at a first location, the first extendable supportelement being operable between an activated control state, in which thefirst extendable support element is actuatable to expand so as to inducemovement of the first end away from the body, and a deactivated controlstate, in which the first extendable support element is not actuatableto expand; a second extendable support element connected to the body andhaving a second end movable away from the body at a second location, thesecond extendable support element being operable between an activatedcontrol state, in which the second extendable support element isactuatable to expand so as to induce movement of the second end awayfrom the body, and a deactivated control state, in which the secondextendable support element is not actuatable to expand; and a tool forcontrolling the expansion of the first and second extendable supportelements, wherein the tool is selectively positionable with respect tothe body in one of a plurality of pre-defined positions, each of theplurality of pre-defined positions being defined by a differentcombination of activated and deactivated control states of the first andsecond extendable support elements.
 17. The system of claim 16, whereinthe tool is configured to actuate the expansion of the first and secondextendable support elements.
 18. The system of claim 16, wherein theimplant further includes a channel configured to guide movement of thetool between the plurality of pre-defined positions.
 19. The system ofclaim 16, wherein the first and second extendable support elements areconfigured to be extended by fluid.
 20. A method of expanding a spinalimplant positioned between a first vertebral body and a second vertebralbody, comprising: positioning a tool with respect to the spinal implantto a selected one of a plurality of pre-defined positions, wherein thespinal implant includes a body having a first surface for engaging thefirst vertebral body, a first extendable support element connected tothe body at a first location, and a second extendable support elementconnected to the body at a second location, each of the first and secondextendable support elements being operable between an activated controlstate, in which expansion of the respective extendable support elementis controllable by the tool, and a deactivated control state, in whichexpansion of the respective extendable support element is notcontrollable by the tool, and wherein each of the plurality ofpre-defined positions of the tool is defined by a different combinationof activated and deactivated control states of the first and secondextendable support elements; and expanding at least one of the first orsecond extendable support elements such that the first or second end ofthe respective first or second extendable support element moves awayfrom the body.